Three dimensional (3D) optical imaging systems are capable of providing distance measurements and a depth image of the objects within the capture area. Such systems are currently used in gaming and multimedia applications, for example, to provide human identification and gesture recognition, as well as in a wide variety of other applications, such as the inspection of semiconductors and other goods, computer-aided design (CAD) verification, robot vision, and geographic surveys. Generally, 3D optical imaging systems include an optical pattern projection system including a light source for illuminating objects. The 3D optical imaging system further includes a light receptor such as a 3D camera for receiving light reflected from an object and forming a 3D image of the object from the reflected light.
In some applications, a diffractive optical element is used in the optical pattern projection system for creating the desired projection pattern. The structure of the diffractive optical element is related to the optical characteristics of the diffractive optical element and the optical pattern projection system. Although existing test systems and methods for the inspection of the diffractive optical element have generally been adequate for their intended purposes, they have not been entirely satisfactory in all respects.